Experimental aortic lesions of acute serum sickness in rabbits.

The mechanisms by which serum sickness cause lesions in the aortic intima are not known. The early aortic lesions of serum sickness detected by permeability to Evans blue dye were studied morphologically to determine the chronologic sequence of lesion initiation and immunochemically with fluorescein-labeled rabbit IgG and bovine serum albumin to detect the presence of antigen and antibody. The topographic localization of lesions and the morphologic changes observed suggest that endothelial injury occurs first, probably due to immune complex deposition, and that platelets play a secondary or reactive role in the process.